class_docstr: Parses the logs from S3 based on the S3 logging format:
  http://docs.aws.amazon.com/AmazonS3/latest/dev/LogFormat.html
  
  Aggregates a user's daily requests by user agent and operation
  
  Outputs date_time, requester, user_agent, operation, count
code: def steps(self):
      return [self.mr(mapper=self.mapper, reducer=self.reducer)]
  
file_path: data-science-ipython-notebooks/mapreduce/mr_s3_log_parser.py
imports: import time
  from mrjob.job import MRJob
  from mrjob.protocol import RawValueProtocol, ReprProtocol
  import re
label_desc: Use image node_id 4 for calling the MrS3LogParser obj's underlying member method code with example usage: obj.steps() and returns: list